1. Field of the Invention
The present invention generally relates to a micro-electro-mechanical systems (MEMS) structure, and more particularly, to a diaphragm of an MEMS electroacoustic transducer.
2. Description of Related Art
Electroacoustic transducers typically employ a diaphragm to convert a sound wave into an electrical signal, or convert an electrical signal into a sound wave, which can be used as microphones or speakers. The electroacoustic transducers have applications in a wide variety of fields. For example, in the computer and communication industries, the electroacoustic transducers can be used in products, such as, cell phones, digital cameras, hands-free sets, notebook computers, or the like. In the bio-medical device industry, the electroacoustic transducers can be used in products, such as, hearing aids, bionic ears, or the like.
With rapid development in the electronics industry and continuous advancing in the semiconductor fabrication process and semiconductor package technology, the electroacoustic transducers are being developed toward multifunction. In order to be light, small, thin, power-saving and inexpensive, the electroacoustic transducer are being developed with a trend toward micro electroacoustic transducers that can be incorporated into chips made by the semiconductor fabrication process.
A micro-electro-mechanical systems (MEMS) electroacoustic transducer is such a product that has mechanical and electronic elements incorporated on a silicon wafer using an integrated circuit technology. One example of the MEMS electroacoustic transducer is an MEMS microphone. Currently, the MEMS microphones are usually designed based on capacitive principles. In the capacitive microphone, electrodes are mounted on a flexible diaphragm and a rigid back plate, respectively. A very small backside cavity exists between the diaphragm and the back plate so that the diaphragm can freely vibrate in response to the sound waves. A change in an electric field between the vibrating diaphragm and the back plate results in an electrical signal in an electrical circuit.
However, the diaphragm of the current MEMS electroacoustic transducer typically includes a pattern layer consisting of a plurality of separate mesh patterns. These patterns in the pattern layer may not match the pattern of the sound wave, which may cause the vibration of the diaphragm to be non-uniform and hence poor performance of the MEMS electroacoustic transducer.